Changes in Chemical Properties of an Oxisol Due to Gypsum Application

ABSTRACT

The increasing demand for fertilizers and the fact that the world reserves of phosphorus (P) and potassium (K) are depletable make appropriate soil management a critical factor in agriculture. Techniques for the fertilizer use and soil acidity corrective are becoming increasingly necessary to minimize the cost of yield and increase the nutrient efficiency. In view of the aforementioned, the present study aimed to assess the effects of gypsum application on the leaching of cations in the soil profile. A completely randomized design in a 5 × 4 factorial arrangement, with five replicates, was used. The treatments corresponded to five gypsum rates (0, 1, 2, 4, and 8 magnesium (Mg) ha⁻¹) applied on broadcast of soil and at four depth sampled (0–5, 6–10, 11–15, and 16–20 cm). Gypsum application increased the fertility in depth, with the leaching of cations. There was an increase in soil pH, exchangeable K⁺ and calcium (Ca²⁺), sulfur (S–SO₄²⁻), P, boron (B), and manganese (Mn) concentration, cation exchange capacity (CEC), K⁺ and Ca²⁺ saturation, Ca²⁺/Mg²⁺, Ca²⁺/K⁺, and K⁺/(Ca²⁺ + Mg²⁺) ratios, and electrical conductivity in soil depth. On the other hand, there was a decrease in exchangeable Mg²⁺ and potential acidity hydrogen and aluminum (H⁺ + Al³⁺), available silicon (Si), Mg²⁺ saturation, and Ca²⁺/K⁺ and Mg²⁺/K⁺ ratio. These results demonstrate that the gypsum application in an Oxisol with 690 g kg⁻¹ of clay improves the root system with a significant increase in the soil fertility in the profile.

KEYWORDS:

• Basic cations
• electrical conductivity
• gypsum application
• soil fertility